Denon DRA-800H Service Manual page 81

Check the I2C communication line.
YES
Check item(3-3.4.). Check the I2C communication line :
Check the CPU.
Is the "I2C" waveform of the HDMI OSD [IC731] correct (like the one
shown in the diagram) when the power is turned on?
A_CK
A_DA
IC731
YES NO
Check item(3-3.5.). Check the I2C communication line :
Check HDMI OSD [IC731], CPU [IC751] patterns as well as soldering.
If there is no problem, go to the next step.
Check the HDMI Rx.
Remove the damping resistor [R7323/R7324]
of [IC731].
Is the "I2C" waveform correct?
YES
OSD [IC731] is faulty.
Replace with a new device.
Recheck from check item (3.1.).
If it does not work, replace the PCB.
*The diagram shows an example.
(Signal patterns vary depending on the
timing.)
Points for checking waveforms
- Crest value (3.3V normally)
- Signal change
- SCL frequency (400kHz normally)
Voltage scale：1.0V/div
Time scale：10us/div
NO CPU [IC751] is faulty.
Replace with a new device.
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